What is the approximate $pH$ value for a solution,if $pH$ paper turns pink when dipped into it?

What will be the action of the following substances on litmus paper? Dry $HCl$ gas,Moistened $NH_3$ gas,Lemon juice,Carbonated soft drink,Curd,Soap solution.

$(i)$ Name the products obtained in the chlor-alkali process.
$(ii)$ Name the gases liberated at the anode and at the cathode,respectively.
$(iii)$ Name the solution which is used as raw material in this process.

Write true or false for the following statement:
Acids that give rise to more $H^+$ ions are said to be strong acids,and acids that give less $H^+$ ions are said to be weak acids.

What precaution must be taken while diluting a concentrated acid?

On what basis are acids classified as strong and weak acids?